Sun Xia, Zhang Min, El-Zaatari Mohamad, Huffnagle Gray B, Kao John Y
Department of Pharmacology, School of Medicine, Shandong University, Jinan, Shandong, China.
Department of Internal Medicine, Division of Gastroenterology, University of Michigan Health System, Ann Arbor, MI, USA.
Helicobacter. 2017 Apr;22(2). doi: 10.1111/hel.12366. Epub 2016 Dec 8.
We previously demonstrated that H. pylori infection leads to increased induction of regulatory T cells in local and systemic immune compartments. Here, we investigate the role of CCR2 in the tolerogenic programing of dendritic cells in a mouse model of H. pylori infection.
CCR2 deficient (CCR2KO) mice and wild-type (Wt) mice infected with H. pylori SS1 strain were analyzed by qPCR and FACS analysis. In vitro, bone marrow-derived DC on day 6 from CCR2KO and Wt mice cocultured with or without H. pylori were examined to determine the impact of CCR2 signaling on dendritic cells function by qPCR, ELISA, and FACS analyses.
Acute H. pylori infection was associated with a threefold increase in CCR2 mRNA expression in the gastric mucosa. H. pylori-infected CCR2KO mice exhibited a higher degree of mucosal inflammation, that is, increased gastritis scores and pro-inflammatory cytokine mRNA levels, but lower degree of H. pylori gastric colonization compared to infected Wt mice. Peripheral H. pylori-specific immune response measured in the CCR2KO spleen was characterized by a higher Th17 response and a lower Treg response. In vitro, CCR2KO bone marrow-derived DC was less mature and shown a lower Treg/Th17 ratio. Moreover, blockade of CCR2 signaling by MCP-1 neutralizing antibody inhibited H. pylori-stimulated bone marrow-derived DC maturation.
Our results indicate that CCR2 plays an essential role in H. pylori-induced immune tolerance and shed light on a novel mechanism of CCR2-dependent DC Treg induction, which appears to be important in maintaining mucosal homeostasis during H. pylori infection.
我们之前证明幽门螺杆菌感染会导致局部和全身免疫区室中调节性T细胞的诱导增加。在此，我们在幽门螺杆菌感染的小鼠模型中研究CCR2在树突状细胞耐受性编程中的作用。
通过qPCR和流式细胞术分析感染幽门螺杆菌SS1菌株的CCR2缺陷（CCR2KO）小鼠和野生型（Wt）小鼠。在体外，对来自CCR2KO和Wt小鼠第6天的骨髓来源的树突状细胞与或不与幽门螺杆菌共培养进行检测，通过qPCR、ELISA和流式细胞术分析来确定CCR2信号对树突状细胞功能的影响。
急性幽门螺杆菌感染与胃黏膜中CCR2 mRNA表达增加三倍相关。与感染的Wt小鼠相比，感染幽门螺杆菌的CCR2KO小鼠表现出更高程度的黏膜炎症，即胃炎评分和促炎细胞因子mRNA水平增加，但幽门螺杆菌胃定植程度较低。在CCR2KO脾脏中检测到的外周幽门螺杆菌特异性免疫反应的特征是Th17反应较高，Treg反应较低。在体外，CCR2KO骨髓来源的树突状细胞不太成熟，Treg/Th17比值较低。此外，MCP-1中和抗体阻断CCR2信号可抑制幽门螺杆菌刺激的骨髓来源的树突状细胞成熟。
我们的结果表明CCR2在幽门螺杆菌诱导的免疫耐受中起重要作用，并揭示了CCR2依赖性树突状细胞Treg诱导的新机制，这在幽门螺杆菌感染期间维持黏膜稳态中似乎很重要。
